Method and apparatus for transmitting/receiving control channel in wireless communication system

ABSTRACT

A control channel transmission/reception method and an apparatus for transmitting/receiving control channels using a resource allocation scheme applicable regardless of reference signal transmission or whether the reference signal is transmitted in distributed transmission mode or localized transmission mode are provided. The control channel transmission method includes mapping a Demodulation Reference Signal (DMRS) to Resource Elements (REs) of a Resource Block (RB) for transmitting a control channel, mapping the control channel to the REs numbered with numbers of predetermined number of Resource Element Groups (REGs) in a frequency-first ascending order cyclically, with the exception of the REs to which the DMRS is mapped, and transmitting the DMRS and the control channel.

PRIORITY

This application claims the benefit under 35 U.S.C. §119(e) of a U.S.Provisional application filed on Apr. 30, 2012 in the U.S. Patent andTrademark Office and assigned Ser. No. 61/640,111, and under 35 U.S.C.§119(a) of a Korean patent application filed on Apr. 26, 2013 in theKorean Intellectual Property Office and assigned Serial No.10-2013-0046497, the entire disclosure of each of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control channeltransmission/reception method and apparatus of a wireless communicationsystem. More particularly, the present invention relates to a method andapparatus for transmitting/receiving control channels using a resourceallocation scheme that is applicable regardless of reference signaltransmission or whether the reference signal is transmitted in adistributed transmission mode or a localized transmission mode.

2. Description of the Related Art

In a Long Term Evolution (LTE) system, the control channels include aUser Equipment (UE) control channel and a relay control channel. The UEcontrol channel is a control channel using a Common Reference Signal(CRS) which is transmitted as segmented in the time domain anddistributed across the entire band. A control channel (e.g., a PhysicalDownlink Control Channel (PDCCH)) is mapped to a plurality of ControlChannel Elements (CCEs), and a CCE comprises a plurality of ResourceElement Groups (REGs). The control channels are interleaved in unit ofREG and multiplexed across the entire band.

The relay control channel is the control channel transmitted on aspecific frequency band (e.g., a Physical Resource Block (PRB)), andsupports both the CRS-based transmission scheme and a DemodulationReference Signal (DMRS)-based transmission scheme. Similar to PDCCHtransmission, the control channel multiplexing supports both theREG-based distributed transmission and a PRB-based localizedtransmission with the notification to the relay through higher layersignaling.

In contrast to the localized transmission which is performed using boththe CRS-based transmission scheme and the DMRS-based transmissionscheme, the distributed transmission is performed only in distributedtransmission mode. In contrast to the CRS-based transmission in whichthe relay performs channel estimation and channel feedback based on CRS,the DMRS-based transmission is performed in such a way that the channelestimation is performed based on DMRS while channel feedback isperformed based on the CSI-RS.

Accordingly, when the CSI-RS is transmitted in the localizedtransmission mode, the resource amount for control channel in a PRBreduces as much as the CSI-RS. In the distributed transmission mode,because no CSI-RS is transmitted, the control channel is transmitted onthe REGs at predetermined positions of a plurality of PRBs.

The Enhanced PDCCH (E-PDCCH) is the channel designed for transmittingthe control channel at a specific frequency region as the relay controlchannel and transmitted only with DMRS in any of the distributed andlocalized transmission modes. Because E-PDCCH supports the DMRS-baseddistributed transmission unlike the relay control channel, E-PDCCH isalways required to transmit CSI-Reference Signal (RS) for E-PDCCH.Accordingly, when CSI-RS exists in a PRB, the available resource of thePRB varies depending on whether the transmission is performed in thedistributed transmission mode or the localized transmission mode.

Therefore, a need exists for a resource allocation method for controlchannel transmission in both the distributed transmission mode and thelocalized transmission mode.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present invention.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide a resource allocation method for control channeltransmission in both the distributed transmission mode and localizedtransmission mode.

In accordance with an aspect of the present invention, a control channeltransmission method of a base station in a wireless communication systemis provided. The method includes mapping a Demodulation Reference Signal(DMRS) to Resource Elements (REs) of a Resource Block (RB) fortransmitting a control channel, mapping the control channel to the REsin a frequency-first ascending order cyclically with the exception ofthe REs to which the DMRS is mapped, and transmitting the DMRS and thecontrol channel.

In accordance with another aspect of the present invention, a controlchannel reception method of a terminal in a wireless communicationsystem is provided. The method includes determining REs to which a DMRSis mapped in a RB for transmitting a control channel, determining theREs to which the control channel is mapped in a frequency-firstascending order cyclically with the exception of the REs to which theDMRS is mapped, and receiving the DMRS and the control channel accordingto the determined REs.

In accordance with another aspect of the present invention, a controlchannel transmission apparatus of a base station in a wirelesscommunication system is provided. The apparatus includes a transceiverwhich transmits and receives signals to and from a terminal, and acontroller which controls mapping a DMRS to REs of a RB for transmittinga control channel, mapping the control channel to the REs in afrequency-first ascending order cyclically with the exception of the REsto which the DMRS is mapped, and transmitting the DMRS and the controlchannel.

In accordance with another aspect of the present invention, a controlchannel reception apparatus of a terminal in a wireless communicationsystem is provided. The apparatus includes a transceiver which transmitsand receives signals to and from a base station, and a controller whichcontrols determining REs to which a DMRS is mapped in a RB fortransmitting a control channel, determining the REs to which the controlchannel is mapped in a frequency-first ascending order cyclically withthe exception of the REs to which the DMRS is mapped, and receiving theDMRS and the control channel according to the determined REs.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagram illustrating a structure of a resource block fortransmitting control channel from an evolved Node B (eNB) to a UserEquipment (UE) according to an exemplary embodiment of the presentinvention;

FIG. 2 is a flowchart illustrating a control channel transmission methodof an eNB according to an exemplary embodiment of the present invention;

FIG. 3 is a flowchart illustrating a control channel reception method ofa UE according to an exemplary embodiment of the present invention;

FIG. 4 is a block diagram illustrating a configuration of an eNBaccording to an exemplary embodiment of the present invention;

FIG. 5 is a block diagram illustrating a configuration of a UE accordingto an exemplary embodiment of the present invention;

FIG. 6 is a diagram illustrating a structure of a resource blockconfigured by shifting Control Channel Elements (CCEs) in a resourceblock such as, for example, the resource block of FIG. 1 on a frequencyaxis for use in a control channel transmission method according to anexemplary embodiment of the present invention;

FIG. 7 is a diagram illustrating a structure of a resource blockconfigured with Resource Element Groups (REGs) each made up of 4Resource Elements (REs) for use in a control channel transmission methodaccording to an exemplary embodiment of the present invention;

FIG. 8 is a diagram illustrating a structure of a resource blockconfigured with REGs each made up of 4 REs for use in a control channeltransmission method according to an exemplary embodiment of the presentinvention;

FIG. 9 is a diagram illustrating a structure of a resource blockconfigured with REGs made up of 2 or 4 REs for use in a control channeltransmission method according to an exemplary embodiment of the presentinvention;

FIG. 10 is a diagram illustrating a structure of a resource blockconfigured with REGs each made up of 3 consecutive REs for used in acontrol channel transmission method according to an exemplary embodimentof the present invention;

FIG. 11 is a diagram illustrating a structure of a resource blockconfigured by shifting REGs of CCE per symbol in the configuration ofFIG. 10 according to an exemplary embodiment of the present invention;

FIG. 12 is a diagram illustrating a structure of a resource blockconfigured by shifting REGs of CCE in a configuration such as, forexample, the configuration of FIG. 10 according to an exemplaryembodiment of the present invention;

FIG. 13 is a diagram illustrating a structure of a resource blockconfigured with REGs each made up of 6 consecutive REs for use in acontrol channel transmission method according to an exemplary embodimentof the present invention;

FIG. 14 is a diagram illustrating the structure of a resource blockdivided into four CCEs each made up of 3 consecutive subcarriers inwhich symbols are cyclic-shifted in unit of 3 at two or one symbolinterval on a time axis as shown in a left part for use in a controlchannel transmission method according to an exemplary embodiment of thepresent invention; and

FIG. 15 is a diagram illustrating a structure of a resource blockconfigure by applying cyclic shift to a resource block such as, forexample, the resource block of FIG. 14 according to an exemplaryembodiment of the present invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Although the description is directed to the OrthogonalFrequency-Division Multiplexing (OFDM)-based radio communication system,particularly the 3rd Generation Partnership Project (3GPP) EvolvedUniversal Terrestrial Radio Access (EUTRA)-based radio communicationsystem, it will be understood by those skilled in the art that thepresent invention can be applied to other communication systems havingthe similar technical background and channel format, with a slightmodification, without departing from the spirit and scope of the presentinvention.

FIG. 1 is a diagram illustrating a structure of a resource block fortransmitting control channel from an evolved Node B (eNB) to a UserEquipment (UE) according to an exemplary embodiment of the presentinvention.

Referring to FIG. 1, the horizontal axis corresponds to a time axis, andnumbers on the time axis are symbol indices. The vertical axiscorresponds to a frequency axis, and numbers on the frequency axis aresubcarrier indices. The control channel is mapped to the resourceelements of the resource block in unit of Control Channel Element (CCE),and CCE is composed of a predetermined number of Resource Element Groups(REGs).

The control channel may be an Enhanced Physical Downlink Control Channel(E-PDCCH). In this case, the E-PDCCH is allocated a resource in a unitof an extended CCE (eCCE). An eCCE is composed of Enhanced REGs (eREGs).The numbers marked on the Resource Elements (REs) are provided todistinguish among the eREGs and thus the REs belonging to the same REGare numbered with the same number.

As illustrated in FIG. 1, when mapping the control channel to the REs ofthe Resource Block (RB) or the Physical Resource Block (PRB) pair, theeNB maps the control channel such that four CCEs occupy one RE on eachof 12 subcarriers within the PRB for the REs remaining after mappingDemodulation Reference Signal (DMRS).

According to exemplary embodiments of the present invention such as, forexample, the exemplary embodiment of the present invention of FIG. 1,the resource block may include four CCEs and, in this case, the eNB mapsthe four CCEs, CCE 0 to CCE 3, to the REs from the position of symbolindex 0 and subcarrier index 0 in the ascending order subcarrier indexalternately. When the mapping has completed to the 12 subcarrier indicesfor the symbol index 0 (e.g., once the mapping has completed to the 12subcarrier indices for the symbol index 0), the mapping continues in theascending order of the subcarriers for the next symbol index 1.Accordingly, the same CCE is mapped to every 4th RE.

According to an exemplary embodiment of the present invention, one CCEmay include two REGs as shown in FIG. 1. Accordingly, 8 REGs areincluded in one RB, because one RB includes four CCEs. If such a schemeis applied to the resource allocation method according to an exemplaryembodiment of the present invention, 8 REGs are mapped in a circularmanner which increases the subcarrier index of RE for each symbol. Forexample, the same REG's RE appears at every 8th subcarrier for the samesymbol from the viewpoint of frequency axis. However, exemplaryembodiments the present invention are not limited this configuration.For example, the number of REGs constituting one CCE can be changed.

When mapping the control channel in the PRB, the same eREG is mapped tothe REs at every 8th subcarrier index, incrementing the symbol index by1 at every 12 subcarriers. Accordingly, a total of 8 eREGs are arrangedin the ascending order of the subcarrier index as shown in FIG. 1.

If eREGx and eREGx+4 constitute one eCCE as shown in FIG. 1, each eCCEoccupies the subcarriers at an interval of 4 REs. Although FIG. 1 isdirected to the case in which an eREG consists of REs positioned atevery 8 REs, the interval between two REs for eREG can be changed. Forexample, the same result as the exemplary embodiment of the presentinvention illustrated in FIG. 1 is reached if an eREG comprises REspositioned at an interval of 16 subcarriers, if the total number ofeREGs is 16, and if eREGx, eREGx+2, eREGx+4, eREGx+8 constitute oneeCCE.

In the typical relationship between eREG and eCCE, the eREG index usedas eCCE index n is expressed as (n mod N_CCE)+j*N_CCE. N_CCE denotes thenumber of CCEs per PRB which is 4 the exemplary embodiment of thepresent invention illustrated in FIG. 1, n denotes the eCCE index, and jdenotes the eREG index. In the case that one eCCE comprises 2 eREGs asshown in FIG. 1, j=0 and 1, eREG index of eCCE 0 is 0, 4, and eREG indexof eCCE 1 is 1, 5.

According to exemplary embodiments of the present invention, the indicesof eREGs corresponding to an eCCE are used in different PRBs (e.g., inthe distributed transmission mode).

In the above-described control channel mapping procedure, the eNBconsiders only DMRS but does not consider Common Reference Signal (CRS)or CSI-RS. Accordingly, the REs to which CRS and CSI-RS are mapped maybe punctured.

In the case of mapping the control channel as described above, each CCEcan be arranged in a similar frequency distributed pattern in a PRB and,especially when existing CSI-RS and/or CRS are punctured, it is possibleto maintain the punctured resource amount identically in the CCEs. Also,it is possible to configure the eREG and eCCE at the same positionsregardless of the position and amount of CRS and CSI-RS.

FIG. 2 is a flowchart illustrating a control channel transmission methodof an eNB according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the eNB sends to the UE the control channelconfiguration information at step 210. The configuration information canbe performed through Radio Resource Control (RRC) signaling and includeinformation on the region for control channel and a DMRS port in theresource block. In the case in which the control channel information istransmitted through a physical channel, step 210 can be omitted.

Thereafter, the eNB maps DMRS in a PRB or PRB pair at step 220.

Thereafter, the eNB maps the control channel to REs remaining aftermapping the DMRS in the PRB or PRB pair at step 230. At this time, thecontrol channel mapping is performed as shown in FIG. 1.

For example, the REs corresponding to the RB are numbered with the REGnumbers, jumping the positions at which DMRS is mapped, in such a way ofincrementing the subcarrier index from 0 for the REs of symbol index 0,symbol index increasing whenever all REs of a symbol are allocatedcompletely. The eNB aggregates the REGs comprising the REs numbered withthe same number to form a CCE and maps the control channel to theresource in unit CCE.

The eNB determines whether the RB includes CRS or CSI-RS at step 240.

If the eNB determines that the RB includes CRS or CSI-RS at step 240,the eNB proceeds to step 250 at which the eNB punctures the REs to whichthe CRS or CSI-RS is mapped. Thereafter, the eNB transmits the controlchannel with DMRS to the UE at step 260.

If the eNB determines that the RB does not include CRS or CSI-RS at step240, the eNB proceeds to step 260 at which the eNB transmits the controlchannel with DMRS to the UE.

FIG. 3 is a flowchart illustrating a control channel reception method ofa UE according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the UE receives the control channel configurationinformation at step 310. As described above, the configurationinformation can be received through higher layer signaling (e.g.,through RRC signaling). If the control channel configuration informationis transmitted through a physical channel, step 310 can be omitted.

Thereafter, the UE determines the REs to which DMRS and control channelsare mapped in the RB at step 320.

At step 330, the UE determines whether the control channel is mapped tothe resource excluding the REs to which DMRS is mapped in unit of CCEaccording to the pattern as shown in FIG. 1.

Thereafter, the UE determines whether the RB includes CRS or CSI-RS atstep 340.

If the RB is determined to include CRS or CSI-RS at step 340, the UEproceeds to step 350 at which the UE assumes that the REs correspondingto CRS or CSI-RS has been punctured. Thereafter, the UE receives thecontrol channel with DMRS at step 360.

In contrast, if the RB is determined to not include CRS or CSI-RS atstep 340, the UE proceeds to step 360 at which the UE receives controlchannel with DMRS.

FIG. 4 is a block diagram illustrating a configuration of an eNBaccording to an exemplary embodiment of the present invention.

Referring to FIG. 4, the eNB includes a controller 410, an eREG/eCCEgenerator 420, a Reference Signal (RS) generator 430, and a multiplexer440.

The controller 410 maps DMRS, under the assumption of 4 DMRS ports, tothe eREG in the frequency-first order in PRB in order to configure thecontrol channel to be transmitted.

The eREG/eCCE generator 420 selects PRB for transmitting the controlchannel and chooses eREG to configure eCCE according to an exemplaryembodiment of the present invention.

The RS generator 430 generates CRS and/or CSI-RS.

The multiplexer 440 multiplexes the control channel and the CRS and/orCSI-RS. At this time, the multiplexer 430 performs multiplexing aftersubstituting the eREG including the REs to which the reference signalsare mapped.

FIG. 5 is a block diagram illustrating a configuration of a UE accordingto an exemplary embodiment of the present invention.

Referring to FIG. 5, the UE includes a controller 510, an eREG/eCCEreceiver 520, a channel estimator 530, and a demultiplexer 540.

The controller 510 controls the demultiplexer 540 to demultiplex thesignal received from the eNB and controls the channel estimator 530 toestimate channels with the demultiplexed CRS and CSI-RS for receivingcontrol channel. The controller 510 controls the eREG/eCCE receiver 520to determine the REs to which the control channel is mapped inassociation with eREG and eCCE regardless of the positions of CRS andCSI-RS and controls the eREG/eCCE receiver 520 to receive the controlchannel on the REs excluding REs corresponding to CRS and CSI-RS becausethe eREG and eCCE are configured in consideration of only the DMRSpositions and the CRS and CSI-RS positions have been punctured.

FIG. 6 is a diagram illustrating a structure of a resource blockconfigured by shifting CCEs in a resource block such as, for example,the resource block of FIG. 1 on a frequency axis for use in a controlchannel transmission method according to an exemplary embodiment of thepresent invention.

Referring to FIG. 6, as an example, PRB 1 can be configured as shown inFIG. 1 while PRB 2 as shown in FIG. 6 is configured such that theposition of the CCE is not fixed but distributed across PRBs.

Hereinafter, a description is provided of exemplary embodiments of thepresent invention for resource allocation of the control channel in aresource block.

FIG. 7 is a diagram illustrating a structure of a resource blockconfigured with REGs each made up of 4 REs for use in a control channeltransmission method according to an exemplary embodiment of the presentinvention.

Referring to FIG. 7, the two RE pairs on the two subcarriers at eachpair of the 5th and 6th symbols, the 9th and 10th symbols, and the 12thand 13th symbols make up one REG.

This is an arrangement in consideration of the 2-port CSI-RS positionsand, if the CSI-RS is mapped to the REs numbered with ‘REG A’ (numberedwith circle), the REG is used for CSI-RS transmission, and the controlchannel for the UE using the CCE including the corresponding REG istransmitted as coded and rate-matched with the exclusion of the resourceas much as the REG used for CSI-RS.

In the case in which the RE pairs at the 9th and 10th symbols, four REson the two subcarriers make up an REG. For example, the four REsnumbered with the same number as shown in FIG. 6 make up an REG, andthis is also configured in consideration of the 2-port CSI-RS positions.In the case of allocating the resource for control channel as shown inFIG. 7, the UE may determine a total resource amount with the exceptionof the region allocated for CSI-RS and negate the necessity of positionchange of REG due to the 2-port CSI-RS configuration and thus isadvantageous in multiplexing.

FIG. 8 is a diagram illustrating a structure of a resource blockconfigured with REGs each made up of 4 REs for use in a control channeltransmission method according to an exemplary embodiment of the presentinvention.

Referring to FIG. 8, the REs numbered with the same number on the twoconsecutive subcarriers at each pair of the 5th and 12th symbols and the6th and 13th symbols constitute one REG.

This is an arrangement in consideration of the 4-port CSI-RS positionsand, if the 4-port CSI-RSs are mapped to the REs as numbered with circlein FIG. 8, the corresponding REG is used for CSI-RS transmission, andthe control channel for the UE using the CCE including the correspondingREG is transmitted as coded and rate-matched with the exclusion of theresource as much as the REG used for CSI-RS.

In the case of the REs at the 9th and 10th time symbols, if the REGsnumbered with ‘1’ and ‘4’ numbered with dotted line circles are used forCSI-RS transmission in consideration of 4-port CSI-RS, the REsconfigured on two consecutive subcarriers are not used for controlchannel transmission.

According to exemplary embodiments of the present invention such as, forexample, the exemplary embodiment of the present invention of FIG. 8,the UE rules out the region corresponding to the 4-port CSI-RS positionsin determining the total resource amount so as to negate the necessityof a REG position change caused by the CSI-RS configuration, resultingin an advantage of multiplexing.

FIG. 9 is a diagram illustrating a structure of a resource blockconfigured with REGs made up of 2 or 4 REs for use in a control channeltransmission method according to an exemplary embodiment of the presentinvention.

Referring to FIG. 9, the REs numbered with the same number on the twoconsecutive subcarriers at the 5th, 12th, 6th, and 13th symbols in FIG.9 constitute an REG.

This is an arrangement in consideration of the 2-port and 4-port CSI-RSpositions and, if the 2-port CSI-RSs are mapped to the resourcesnumbered with 1, 2, 3, and 4 (e.g., the resources numbered andillustrated as having circles thereon), the corresponding REs are usedfor CSI-RS transmission, and the control channel for the UE using theCCE including the corresponding REG is transmitted as coded andrate-matched with the inclusion of all the resources of REG used forCSI-RS and then punctured the positions corresponding to CSI-RS andreplaced the punctured region with CSI-RS.

According to exemplary embodiments of the present invention such as, forexample, the exemplary embodiment of the present invention of FIG. 9,because the UE is capable of decoding and rate-matching all the controlchannel with the same size of CCE regardless of 2-port or 4-port CSI-RSconfiguration and the REs punctured for CSI-RS are identical in allCCEs, minimizing the performance difference between control channels ispossible.

FIG. 10 is a diagram illustrating a structure of a resource blockconfigured with REGs each made up of 3 consecutive REs for used in acontrol channel transmission method according to an exemplary embodimentof the present invention.

Referring to FIG. 10, the REGs are configured by taking only the DMRSpositions into consideration.

In the case in which the REGs are configured in consideration of CRS inthe exemplary embodiments of the present invention of FIGS. 7 to 9, if 4CCEs are transmitted in a PRB, the REG including up to 3 or 2 CCEs, butnot 4 CCEs, can be used in view of symbol. Meanwhile, in the case of REGconfiguration with 3 REs, up to 4 or 2 REGs can be transmitted at onesymbol and thus allocation of the resource of the same CCE is possible.

In the case of configuring REGs as shown in FIG. 9, the REGs arenumbered with numbers. At this time, the REGs numbered with indices atthe interval of 4 constitute the same CCE. Accordingly, when configuringCCE for control channel, although the coding and rate matching areperformed to the same number of REs regardless of CCE, the REGs arearranged as shown in FIG. 10. At this time, if CRS and CSI-RS aretransmitted, the REs for the control channel are punctured and replacedwith the CRS or CSI-RS. According to the exemplary embodiment of thepresent invention of FIG. 10, maintaining the same performance on theCCEs by puncturing the same amount of REs for the CRS and CSI-RS ispossible.

FIG. 11 is a diagram illustrating a structure of a resource blockconfigured by shifting REGs of CCE per symbol in a configuration suchas, for example, the configuration of FIG. 10 according to an exemplaryembodiment of the present invention.

Referring to FIG. 11, a CCE can be distributed across the frequency bandwithin a PRB so as to avoid the performance difference caused by thechannel estimation difference between frequency bands.

FIG. 12 is a diagram illustrating a structure of a resource blockconfigured by shifting REGs of CCE in a configuration such as, forexample, the configuration of FIG. 10 according to an exemplaryembodiment of the present invention.

Referring to FIG. 12, preventing a CCE from being limited to specificregion in different PRBs is possible. Thus, especially when a controlchannel is mapped to multiple PRBs, a performance difference caused bychannel estimation difference between frequency bands may be avoided.For example, configuring PRB 1 as shown in FIG. 10 while configuring PRB3 as shown in FIG. 12 is possible.

FIG. 13 is a diagram illustrating a structure of a resource blockconfigured with REGs each made up of 6 consecutive REs for use in acontrol channel transmission method according to an exemplary embodimentof the present invention.

Referring to FIG. 13, in the case of configuring an REG with 6 REs, itis possible to allocate the same resource of CCE because up to 2 REGscan be transmitted across one time symbol as shown in FIG. 12. In FIG.12, REGs are numbered with respective indices, and the REGs having theindices at the interval of 4 constitute a CCE.

Accordingly, it is possible to perform coding and rate matching to thesame number of REs regardless of CCE in configuring CCEs of controlchannel and arrange the REGs as shown in FIG. 13. At this time, if CRSand CSI-RS are transmitted, the control channel mapped to thecorresponding REs are punctured and replaced with the CRS and CSI-RS.According to the exemplary embodiment of the present invention of FIG.13, if the control channel is punctured due to the CRS and CSI-RS, thepuncturing is performed for relatively the same amount of the REs in theCCEs so as to maintain the same performance between CCEs.

FIG. 14 is a diagram illustrating the structure of a resource blockdivided into four CCEs each made up of 3 consecutive subcarriers inwhich symbols are cyclic-shifted in unit of 3 at two or one symbolinterval on a time axis as shown in a left part for use in a controlchannel transmission method according to an exemplary embodiment of thepresent invention. FIG. 15 is a diagram illustrating a structure of aresource block configured by applying cyclic shift to a resource blocksuch as, for example, the resource block of FIG. 14 according to anexemplary embodiment of the present invention.

Referring to FIG. 14, it is possible to transmit one CCE across theentire PRB while the resources at the CSI-RS transmission positions ofsymbols 5, 6, 9, 10, 12, and 13 do not influence the CCE. This method isadvantageous in performing rate matching in consideration of CSI-RS orCRS overhead.

Referring to FIG. 15, the method of FIG. 14 may apply different cyclicshifts to the PRB x and PRB y as shown in FIG. 15.

As described above, according to exemplary embodiments of the presentinvention, the control channel transmission/reception method andapparatus may configure REGs and CCEs to allocate the resource forcontrol channel transmission efficiently using specific resource regionsand DMRS and multiplexing the control channel to be transmitted in boththe distributed and localized modes in consideration of the RS positionsand overhead.

According to exemplary embodiments of the present invention, the controlchannel transmission/reception method and apparatus for use in thewireless communication system may arrange CCEs for control channel insimilar frequency distributed manner in PRB and maintaining, when it isnecessary to puncture the control channel at REs for CSI-RS and CRS, thesame amount of resource to be punctured among the CCEs.

It will be appreciated that exemplary embodiments of the presentinvention according to the claims and description in the specificationcan be realized in the form of hardware, software or a combination ofhardware and software.

Any such software may be stored in a non-transitory computer readablestorage medium. The non-transitory computer readable storage mediumstores one or more programs (software modules), the one or more programscomprising instructions, which when executed by one or more processorsin an electronic device, cause the electronic device to perform a methodof the present invention.

Any such software may be stored in the form of volatile or non-volatilestorage such as, for example, a storage device like a Read Only Memory(ROM), whether erasable or rewritable or not, or in the form of memorysuch as, for example, Random Access Memory (RAM), memory chips, deviceor integrated circuits or on an optically or magnetically readablemedium such as, for example, a Compact Disk (CD), Digital Versatile Disc(DVD), magnetic disk or magnetic tape or the like. It will beappreciated that the storage devices and storage media are exemplaryembodiments of machine-readable storage that are suitable for storing aprogram or programs comprising instructions that, when executed,implement exemplary embodiments of the present invention. Accordingly,exemplary embodiments provide a program comprising code for implementingapparatus or a method as claimed in any one of the claims of thisspecification and a machine-readable storage storing such a program.

It is to be appreciated that those skilled in the art can change ormodify the exemplary embodiments without departing the technical conceptof this invention. Accordingly, it should be understood thatabove-described exemplary embodiments are essentially for illustrativepurpose only but not in any way for restriction thereto. Thus the scopeof the invention should be determined by the appended claims and theirlegal equivalents rather than the specification, and various alterationsand modifications within the definition and scope of the claims areincluded in the claims.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A control channel transmission method of a base station in a wireless communication system, the method comprising: mapping a Demodulation Reference Signal (DMRS) to Resource Elements (REs) of a Resource Block (RB) for transmitting a control channel; mapping the control channel to the REs in a frequency-first ascending order cyclically with the exception of the REs to which the DMRS is mapped; and transmitting the DMRS and the control channel.
 2. The method of claim 1, wherein the mapping of the control channel comprising: mapping the control channel in an ascending order of frequency index in a symbol of the RB; and incrementing a time index to continue mapping the control channel, whenever the symbol is full, repeatedly.
 3. The method of claim 1, wherein the REs are numbered with a predetermined amount of Resource Element Group (REG) numbers cyclically.
 4. The method of claim 3, wherein the REs numbered with the REG numbers at a symbol of the RB are assigned in an ascending order of frequency index and then at another symbol by incrementing time index, repeatedly.
 5. The method of claim 3, further comprising: configuring each of the REGs by aggregating the REs numbered with a same REG number, wherein the mapping of the control channel comprises aggregating the REGs assigned respective REG numbers at least one Control Channel Element (CCE).
 6. The method of claim 1, wherein the mapping of the control channel comprises puncturing at the REs to which a Cell-specific Reference Signal (CRS) or a Channel State Information Reference Signal (CSI-RS) is mapped.
 7. The method of claim 1, wherein the control channel corresponds to an Enhanced Physical Downlink Control Channel (E-PDCCH).
 8. A control channel reception method of a terminal in a wireless communication system, the method comprising: determining Resource Elements (REs) to which a Demodulation Reference Signal (DMRS) is mapped in a Resource Block (RB) for transmitting a control channel; determining the REs to which the control channel is mapped in a frequency-first ascending order cyclically with the exception of the REs to which the DMRS is mapped; and receiving the DMRS and the control channel according to the determined REs.
 9. The method of claim 8, wherein the control channel is mapped in an ascending order of frequency index in a symbol of the RB while incrementing a time index to continue mapping the control channel, whenever the symbol is full, repeatedly.
 10. The method of claim 8, wherein the REs are numbered with a predetermined amount of Resource Element Group (REG) numbers cyclically.
 11. The method of claim 10, wherein the REs numbered with the REG numbers at a symbol of the RB are assigned in an ascending order of frequency index and then at another symbol by incrementing time index, repeatedly.
 12. The method of claim 10, further comprising: configuring each of the REGs by aggregating the REs numbered with the same REG number, wherein the mapping of the control channel comprises aggregating the REGs assigned respective REG numbers at least one Control Channel Element (CCE).
 13. The method of claim 8, wherein the determining of the REs to which the control channel is mapped comprises assuming puncture at the REs to which a Cell-specific Reference Signal (CRS) or a Channel State Information Reference Signal (CSI-RS) is mapped.
 14. The method of claim 8, wherein the control channel corresponds to an Enhanced Physical Downlink Control Channel (E-PDCCH).
 15. A control channel transmission apparatus of a base station in a wireless communication system, the apparatus comprising: a transceiver which transmits and receives signals to and from a terminal; and a controller which controls mapping a Demodulation Reference Signal (DMRS) to Resource Elements (REs) of a Resource Block (RB) for transmitting a control channel, mapping the control channel to the REs in a frequency-first ascending order cyclically, with the exception of the REs to which the DMRS is mapped, and transmitting the DMRS and the control channel.
 16. The apparatus of claim 15, wherein the controller maps the control channel in an ascending order of frequency index in a symbol of the RB, and increments a time index to continue mapping the control channel, whenever the symbol is full, repeatedly.
 17. The apparatus of claim 15, wherein the REs are numbered with a predetermined amount of Resource Element Group (REG) numbers cyclically.
 18. The apparatus of claim 17, wherein the REs numbered with the REG numbers at a symbol of the RB are assigned in an ascending order of frequency index and then in another symbol by incrementing time index, repeatedly.
 19. The apparatus of claim 17, wherein the controller controls configuring each of the REGs by aggregating the REs numbered with a same REG number, and wherein the mapping of the control channel comprises aggregating the REGs assigned respective REG numbers at least one Control Channel Element (CCE).
 20. The apparatus of claim 15, wherein the controller controls puncturing at the REs to which a Cell-specific Reference Signal (CRS) or a Channel State Information Reference Signal (CSI-RS) is mapped.
 21. The apparatus of claim 15, wherein the control channel corresponds to an Enhanced Physical Downlink Control Channel (E-PDCCH).
 22. A control channel reception apparatus of a terminal in a wireless communication system, the apparatus comprising: a transceiver which transmits and receives signals to and from a base station; and a controller which controls determining Resource Elements (REs) to which a Demodulation Reference Signal (DMRS) is mapped in a Resource Block (RB) for transmitting a control channel, determining the REs to which the control channel is mapped in a frequency-first ascending order cyclically with the exception of the REs to which the DMRS is mapped, and receiving the DMRS and the control channel according to the determined REs.
 23. The apparatus of claim 22, wherein the control channel is mapped in an ascending order of frequency index in a symbol of the RB while incrementing a time index to continue mapping the control channel, whenever the symbol is full, repeatedly.
 24. The apparatus of claim 22, wherein the REs are numbered with a predetermined amount of Resource Element Group (REG) numbers cyclically.
 25. The apparatus of claim 24, wherein the REs numbered with the REG numbers at a symbol of the RB are assigned in an ascending order of frequency index and then in another symbol by incrementing time index, repeatedly.
 26. The apparatus of claim 24, wherein the controller controls configuring each of REGs by aggregating the REs numbered with the same REG number, and wherein the mapping of the control channel comprises aggregating the REGs assigned respective REG numbers at least one Control Channel Element (CCE).
 27. The apparatus of claim 22, wherein the controller assumes puncture at the REs to which a Cell-specific Reference Signal (CRS) or a Channel State Information Reference Signal (CSI-RS) is mapped.
 28. The apparatus of claim 22, wherein the control channel corresponds to an Enhanced Physical Downlink Control Channel (E-PDCCH). 